Synthesis and properties of novel polyimides containing fluorinated alkoxyside groups

A novel method for the preparation of a fluorinated aromatic diamine was in vestigated. This new diamine contains a fluoroalkoxy (C6F13-C2H4-O-) side c hain and it was synthesised by the reaction of 1H,1H,2H,2H-perfluorooctanol with 2-(4-nitrophenoxy)-4-nitrophenol via the Mitsunobu reaction and subse quent,reduction. This novel diamine was used with different,dianhydrides, 4 ,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), pyromellitic dia nhydride (PMDA) land benzophenonetetracarboxylic dianhydride (BTDA) to prep are polyimides by direct thermal imidization. The polyimide properties such as inherent viscosity, solubility, thermal and surface properties were inv estigated to illustrate the contribution of the fluoroalkoxy group that is attached to the polyimide backbone. The resulting poly-imides possessed goo d thermal properties, the presence of the fluoroalkoxy group did not affect the thermal stability and increased the solubility in common organic solve nts. The glass transition temperatures (T-g) of the fluorinated polyimides were higher than 195 degreesC. The surface tension determined by contact an gle measurements of the polyimide prepared with dianhydride 6FDA and diamin e containing fluorinated alkoxy side group was 25.3 mN . m(-1).